Senior LLM Engineer (Deep-Tech AI)
Location: Basque Country, Spain

We are partnering with a well-funded, rapidly scaling deep-tech company operating at the intersection of advanced AI and next-generation computing to find their next Senior LLM Engineer. Backed by strong commercial traction and integral enterprise clients, this organization is building highly efficient, production-grade AI systems designed to solve complex, real-world problems across multiple industries.

Their team brings together world-class researchers and engineers working on cutting-edge challenges in large-scale model development, optimization, and deployment. This is a rare opportunity to join a highly technical environment where you will directly shape the future of large language models—not just apply them.

As a Senior LLM Engineer, you will take ownership of designing, training, and optimizing large-scale language models from the ground up. This is a hands-on, deeply technical role focused on core model development , not just downstream application or prompt engineering.

Key Responsibilities
Design and train transformer-based models from scratch , including pretraining pipelines at scale
Lead or contribute to post-training workflows (SFT, RLHF, DPO, etc.) and model alignment
Build and optimize data pipelines for large-scale training (curation, deduplication, sampling strategies)
Improve model performance through architecture modifications, training objectives, and efficiency techniques
Conduct rigorous evaluation and benchmarking , going beyond standard metrics
Optimize training and inference performance (memory, throughput, latency) across GPU/HPC environments
Collaborate cross-functionally to integrate models into production systems
Mentor junior engineers and contribute to technical best practices

Required Experience & Skills
Minimum 2+ years of hands-on experience training LLMs or transformer models from scratch (pretraining or equivalent); Machine Learning, Deep Learning, NLP,



Computer Vision
For the Senior title, a minimum of 5+ years and a wider breadth of experience in building deep learning applications e.g. computer vision, audio
Proven experience with end-to-end LLM development , including: Pretraining at scale, fine-tuning (full FT, LoRA, QLoRA, etc.), and model evaluation and iteration
Strong theoretical understanding of transformers, optimization, and deep learning fundamentals
Expertise in Python and modern ML frameworks (e.g., PyTorch, Hugging Face ecosystem)
Experience with distributed training (FSDP, DeepSpeed, Megatron, etc.)
Solid understanding of GPU architectures and performance optimization techniques
Experience working with large datasets and training pipelines at scale
Familiarity with inference optimization tools (e.g., vLLM, TensorRT-LLM)
Strong problem-solving and debugging capabilities in complex training systems

Why Apply?
Work on true LLM innovation , not just downstream applications
Influence the design of next-generation AI systems at scale
Join a highly technical, research-driven environment with real-world impact
Competitive compensation, flexible working, and strong growth trajectory

Recruiter’s Note
We are specifically targeting engineers who have built models, not just used them . If you’ve led or significantly contributed to training pipelines, tackled scaling challenges, or improved model performance at the architecture or systems level - we want to hear from you.

Candidates who only have experience working on prompt engineering, API-based LLM usage, or light fine-tuning of existing models cannot be considered.

If this role is of any interest please apply directly on LinkedIn or send a copy of your CV, referencing the title and location, and with a short intro to [email protected] .

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📌 Senior LLM Engineer (Deep-Tech AI) (Bilbao)
🏢 Talent
📍 Bilbao